This data set provides net primary productivity (NPP) estimates and associated field measurements for six sites located along the 250-km, west-east transect of the Oregon Transect Ecosystem Research Project (OTTER) in the Pacific Northwest.
Leaf area indices, biomass, and NPP vary about 10-fold across the OTTER transect. Leaf area index (LAI) ranges from 0.4 m2/m2 at the Juniper/Sisters site to 8.6 m2/m2 at the Scio western Cascade site. Total NPP follows a similar trend with the Juniper/Sisters site having the lowest NPP value (300 g/m2/yr) and the Scio site having the highest (2,250-2,570 g/m2/yr). Total tree biomass across the transect ranges from to 1,080 g/m2 at Juniper/Sisters to 71,080 g/m2 at Cascade Head. Vegetation intercepts 22% to 99.5% of incident photosynthetically active radiation along the transect.
There is one data file (.csv format) with this data set.
Revision Notes: Only the documentation for this data set has been modified. The data files have been checked for accuracy and are identical to those originally published in 1999.
The NPP data collection contains field measurements of biomass, estimated NPP, and climate data for terrestrial grassland, tropical forest, temperate forest, boreal forest, and tundra sites worldwide. Data were compiled from the published literature for intensively studied and well-documented individual field sites and from a number of previously compiled multi-site, multi-biome data sets of georeferenced NPP estimates. The principal compilation effort (Olson et al., 2001) was sponsored by the NASA Terrestrial Ecology Program. For more information, please visit the NPP web site at http://daac.ornl.gov/NPP/npp_home.html.
Other Data Access Links:
Additional site ancillary data for the OTTER Metolius site are available on the FLUXNET project web site: http://fluxnet.ornl.gov/. Investigators collected data on site vegetation, soil, hydrologic, and meteorological characteristics at the flux tower sites.
More information about the Oregon Transect Ecosystem Research (OTTER) Project and links to additional data (including canopy chemistry, meteorology, field sunphotometer, airborne sunphotometer, and timber measurements) can be found at the project web site: http://daac.ornl.gov/OTTER/otter.shtml. Also included at this web site is a link to the OTTER Project/Campaign Document: http://daac.ornl.gov/OTTER/otter_campaign.html
Figure 1. Coastal Tsuga heterophylla / Picea sitchensis forest in the western coastal range of Oregon, characteristic of the Cascade Head site (Site 1) studied as part of the Oregon Transect Ecosystem Research Project (OTTER). (Photograph taken 1970s by Larry Huditz, United States Forest Service; reproduced by permission of Dr. H. Gholz, University of Florida, USA).
Cite this data set as follows:
Waring, R.H., B. Law, and B. Bond. 2013. NPP Temperate Forest: OTTER Project Sites, Oregon, USA, 1989-1991, R1. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. doi:10.3334/ORNLDAAC/472
This data set was originally published as:
Waring, R.H., B. Law, and B. Bond. 1999. NPP Temperate Forest: OTTER Project Sites, Oregon, U.S.A., 1989-1991. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.
Project: Net Primary Productivity (NPP)
This data set provides above-ground biomass data, above- and below-ground NPP estimates, and associated field measurements for six sites located along the 250-km, west-east transect of the OTTER project. The transect spans the large environmental gradient of western Oregon covering a range of climate regimes and associated forest zones, ranging from lush, coastal forests to dry juniper woodlands. Stands in the five western zones are dominated by even-aged overstories of trees 120-200 years old, although several stands have a few much older individuals. Eastern zone communities are uneven aged but are mature and undisturbed. During the study years (1989-1991), some sites received fertilization treatment while others were controls.
Leaf area indices, biomass, and NPP vary about 10-fold across the OTTER transect. LAI ranges from 0.4 m2/m2 at the Juniper/Sisters site to 8.6 m2/m2 at the Scio western Cascades site. Total tree biomass across the transect ranges from to 1,080 g/m2 at Juniper/Sisters to 71,080 g/m2 at Cascade Head. The foliage biomass ranges from 190 g/m2 at Metolius sites to 1,530 g/m2 at Scio sites. Litterfall followes the trends in foliar biomass, with the exception of the deciduous alder stand (site lA), which sheds all of its foliage annually. The Juniper/Sisters site has the lowest total NPP value (300 g/m2/yr) and the Scio site has the highest (2,250-2,570 g/m2/yr). Below-ground production represents 20% to 32% of total NPP on sites on the western side of the Cascade Mountains and 53% to 60% of total NPP for the east-side stands (sites 5, 5F, and 6). The spatial pattern (west-to-east) of BNPP reflects increasing harshness of the environment. Vegetation intercepts 22% to 99.5% of incident photosynthetically active radiation (PAR) along the transect. The amount of PAR the trees are able to utilize varies from 92% in the coastal rainforests to <25% in the juniper woodland as a result of temperature extremes, drought, and vapor pressure deficit extremes.
Comparisons of NPP predictions made by the FOREST-BGC model to the measured data resulted in an r-squared of 0.82. The remotely sensed data (from broad- and narrow-spectral-band instruments) were capable of providing estimates of leaf area index that could be used in forest ecosystem simulation models to estimate evapotranspiration, photosynthesis, canopy turnover, and net primary productivity over large areas. Remote sensing also provided values for nitrogen content, lignin concentration, chlorophyll, and intercepted photosynthetically active radiation (IPAR). While the extraction of important ecological and environmental information from satellite remotely sensed observations was possible, it was made difficult by atmospheric attenuation and residual cloud cover. See Related Data Sets (including canopy chemistry, meteorology, field sunphotometer, airborne sunphotometer, and timber measurements) at the OTTER project web site: http://daac.ornl.gov/OTTER/otter.shtml.
Table 1. ANPP, BNPP, and TNPP values reported by various published data sources
|File Name or Description||Data Source(s)||Sub-Site||ANPP||BNPP||TNPP|
|ott_npp.txt||Runyun et al. (1994)1||Cascade Head #1||498.8||147.3||646|
|Cascade Head #1A||555.8||218.5||774.3|
|Waring's Woods #2||551||180.5||731.5|
|Santiam Pass #4||242.3||114||356.3|
|ODS||Goltz (1980)||2062 (Juniper site #6 only)||52.31||NA||1052|
|GPPDI_ClassA_NPP_162_R2.csv||Olson et al. (2001b) based on Runyun et al. (1994)||Class A 96 (MI 93) (Cascade Head #1)||499||147||646|
|Class A 94 (MI 91) (Waring's Woods #2)||551||181||732|
|Class A 95 (MI 92) (Scio #3)||831||238||1069|
|Class A 92 (MI 89) (Santiam Pass #4)||242||114||356|
|Class A 93 (MI 90) (Metolius #5)||71||81||152|
|Class A 91 (MI 88) (Juniper/Sisters #5)||57||86||143|
|EMDI_ClassA_NPP_81_R2.csv||Olson et al. (2001b) based on Runyun et al. (1994)||Class A 96 (Cascade Head #1)||499||147||646|
|Class A 94 (Waring's Woods #2)||551||181||732|
|Class A 95 (Scio #3)||831||238||1069|
|Class A 92 (Santiam Pass #4)||242||114||356|
|Class A 93 (Metolius #5)||71||81||152|
|Class A 91 (Juniper/Sisters #5)||57||86||143|
This data set contains a single data file (comma-separated-value format). The file provides NPP estimates and associated field measurements for six sites located along the 250-km, west-east transect of the OTTER project.
Site: Oregon Transect, USA
Site Boundaries:(All latitude and longitude given in decimal degrees)
|Site (Region)||Westernmost Longitude||Easternmost Longitude||Northernmost Latitude||Southernmost Latitude||Elevation|
|Oregon Transect, USA||-124.02||-121.17||44.95||44.27||170 - 1,460|
The study region is a west-to-east transect which extends approximately 250 km from Cascade Head Experimental Forest (44.95 N -124.02 W) along the Pacific Coast of Oregon, north of Lincoln City, to Juniper/Sisters (44.29 N 121.33 W) in the high desert interior near Redmond in central Oregon (Figure 2). The transect spans the large temperature-moisture gradient of Oregon. The six forest ecosystem sites were selected from the same forest community types as from an earlier study of leaf area, biomass, and NPP (Gholz, 1982). Additional considerations in study site selection were year-round accessibility and a secure site nearby for installing a meteorological station. Throughout the Pacific Northwest region, soil nitrogen is known to limit growth. Therefore, subsidiary stands were selected along the transect where nitrogen fertilizer was applied or nitrogen-fixing plants were abundant.
The names and numerical codes associated with each site are provided in Table 2. Together, these study sites display almost the complete range of NPP found in North America.
Table 2. OTTER sites in this study (listed west to east)
|SITE NO.||SITE NAME (TREATMENT)||PHYSIO-GRAPHIC PROVINCE/ELEVATION (M)||DOMINANT SPECIES||LAI (m2/m2)||TOTAL BIO-MASS (g/m2)||NPP (g/m2/yr)||LAT||LON|
|1||Cascade Head (old-growth control)||Western coast range/240||Picea sitch ensis-Tsuga heterophylla||6.4||71,080||1,360||45.05||-123.96|
|1A||Cascade Head (N-fixing)||Western coast range/200||Alnus rubra||4.3||12,030||1,630||45.05||-123.96|
|2||Waring's Woods (none)||Int erior valley/170||Pseudotsuga menziesii||5.3||47,120||1,540||44.60||-123.27|
|3||Scio (control1)||Low elevation west Cascades/800||Tsuga heterophylla-Pseudotsuga menziesii||8.6||40,830||2,250||44.68||-122.61|
|3F||Scio (intensively fertilized2)||Low elevation west Cascades/600||Tsuga heterophylla-Pseudotsuga menziesii||8.6||39,230||2,570||44.68||-122.61|
|4||Santiam Pass (none)||High Cascades summit/1,460||Tsuga mertensiana||2.8||37,030||750||44.42||-121.84|
|5||Metolius (control)||Eastern high Cascades/1,030||Pinus ponderosa||2.0||1,490||320||44.42||-121.67|
|5F||Metolius (fertilized3)||Eastern high Cascades/1,030||Pinus ponderosa||2.0||1,990||320||44.42||-121.67|
|6||Juniper/Sisters (none)||High lava plain/930||Juniperus occidentalis||0.4||1,080||300||44.29||-121.33|
Notes: 1The Scio site #3, a 55 x 55 m mixed stand of western hemlock (Tsuga heterophylla) and Douglas-fir (Pseudotsuga menziesii) had been previously fertilized in 1988 with an aerial application of 300 kg/ha of urea. 2The Scio site #3F was fertilized through 1990 and 1991 with manual application of N twice a year (spring and fall) for a total of 460 kg/ha/yr/. 3The Metolius site #5F, a stand of ponderosa pine (Pinus ponderosa) received surface application of sewage sludge for the 5 years prior to initiation of the OTTER project in 1989. The treated sites were compared to the control or untreated sites. Law and Waring (1994) also used four shrub-dominated study areas adjacent to sites 1, 2, 5, and 6 for IPAR measurements. See Methods section for details.
Climate variation across the transect is extreme, with precipitation ranging from 2,510 mm along the Pacific Coast to 220 mm at the easternmost site. The coastal and valley sites rarely experience snow. The subalpine forest (Santiam Pass) experiences moderate to deep snowpack every year, and freezing temperatures persist for much of the winter, both at Santiam Pass and at the eastern high Cascades (Metolius) and high lava plains (Juniper) sites. Drought is extreme at the interior valley site (Waring's Woods), the Metolius pine site, and the Juniper woodland site. Mean annual temperature varies inversely with elevation, from 11.2 C at Waring's Woods (elevation 170 m) to 6 C at Santiam Pass (elevation 1,460 m). This range in climate influences regional vegetation patterns (Franklin and Dyrness, 1973).
Figure 2. Map of the study area showing the location of sites studied as part of the Oregon Transect Ecosystem Research Project (OTTER). Site 1 = Cascade Head; Site 2 = Waring's Woods; Site 3 = Scio; Site 4 = Santiam Pass; Site 5 = Metolius; Site 6 = Juniper / Sisters. [Major vegetation zones are also shown, after Gholz (1982). Figure reproduced by kind permission of Ecological Applications].
Figure 3. Sub-alpine Tsuga mertensiana woodland at the High Cascades summit, characteristic of the Santiam Pass site (site 4) studied as part of the Oregon Transect Ecosystem Research Project (OTTER). (Two-meter snowpacks are present for most of the winter. Photograph taken December 1976 by Dr. H. Gholz, University of Florida, USA).
Figure 4. Pinus ponderosa woodland in the Eastern High Cascades, characteristic of the Metolius site (site 5) studied as part of the Oregon Transect Ecosystem Research Project (OTTER). (Artemesia tridentata var. tridentata and the nitrogen-fixing shrub Purshia tridentata are present in the understory. Photograph taken about 1976 by Dr. H. Gholz, University of Florida, USA).
Figure 5. Open woodland of Juniperus occidentalis on the high lava plain of Central Oregon, characteristic of the Juniper/ Sisters site (site 6) studied as part of the Oregon Transect Ecosystem Research Project (OTTER). (The largest trees are about 350 years old. Photograph taken about 1976 by Dr. H. Gholz, University of Florida, USA).
The size of each vegetated plot ranged from 0.25 to 0.41 ha. Twenty (20) circular plots of 50 m2 were established randomly within each stand to provide good estimates of above-ground tree biomass.
Three (3) years (1989/01/01-1991/12/31).
Principal field campaigns were planned to match changes in ecosystem function throughout each year: (1) February-March (pre-budbreak); (2) May-June (budburst); (3) August (full expansion of foliage); and (4) September-October (foliage of deciduous trees and shrubs in full autumn color). Foliage biomass samples were collected during July 1990. Specific leaf areas of foliage (used in LAI calculations) were measured from mid-canopy foliage collected in early August. LAI determinations with the LAI-2000 were made during a l-wk period in June 1991. Shrubs and herbs were harvested at the end of the growing season, before litterfall loss, for biomass and production measurements. Woody growth measurements were made of the current-year's ring width (1990) and of the previous 5 years. Meteorological data including air temperature, relative humidity, precipitation, and shortwave (400-1,200 nm) incoming radiation were recorded by minute and stored as hourly averages. Measurements of the fraction of photosynthetically active radiation intercepted (IPAR) were made during July-August 1991and in July 1992 between 1200 and 1400 local solar time.
Data File Information
Table 3. Data files in this data set archive
|FILE NAME||TEMPORAL COVERAGE||FILE CONTENTS|
|ott_npp.csv||1989/01/01-1991/12/31||Above-ground biomass data, above- and below-ground net primary production (NPP) estimates, and associated field measurements for six sites located along the 250-km, west-east OTTER transect|
NPP Data. NPP estimates for the OTTER transect sites are provided in one file (comma-separated-value format format). The first 18 lines are metadata; data records begin on line 19. The value -999.9 is used to denote missing values. All NPP units are in g/m2 (dry matter weight).
Table 4. Column headings in NPP File
|parameter||Parameters measured (see definitions in Table 5)|
|units||Unit of measure|
|reference||Reference to reported data (complete citations are listed at end of the data file)|
Table 5. Parameter definitions in NPP file
|site_name||Site where data were gathered||
|treatment||Indicates whether the site was naturally or chemically fertilized or not (see Table 2 and Runyon et al., 1994)||
|numerical_code||Site identification number||
|latitude||Latitude of site where data were collected||
|Longitude of site where data were collected||
|elevation||Elevation (above sea level) of site where data were collected||
|slope||Degree of inclination||
|physiographic_province||Landform region delineated according to similar terrain that has been shaped by a common geologic history; from Franklin and Dyrness (1973)||text|
|dominant_species||Scientific name of tree species dominating the forest stand||text|
|basal_area||Basal area of forest stand calculated by field measurements of tree trunk DBH||m2/ha|
|stem_density||Stem density of forest stand (number of stems > 5 cm DBH per hectare)||stem/ha|
|avg_max_canopy_height||Average maximum canopy height for stand, where measured||m|
|precip_1990||Annual precipitation for 1990 for each site derived from onsite meteorological station except for Site 6 where data are from 20-yr NOAA averages for Redmond, Oregon||mm|
|mean_annual_temp_1990||Mean annual air temperature for 1990 for each site derived from onsite meteorological station except for Site 6 where data are from 20-yr NOAA averages for Redmond, Oregon||degrees C|
|incident_PAR_1||Total annual incident PAR reported by Pierce et al. (1994)||MJ/m2/year|
|LAI_max||Mean LAI [average of results from three different methods for estimating LAI (see below)]||m2/m2|
|LAI_Decagon_ceptometer||LAI estimated from measurements of transmitted PAR recorded on cloudless days|
|LAI_LAI_2000||LAI estimated with the LI-COR LAI-2000 instrument|
|LAI_sapwood||LAI determined from the ratio between leaf area and area of sapwood at the base of the live tree crown|
|incident_PAR_2||Total annual incident PAR reported by Runyon et al. (1994)||MJ/m2/year|
|intercepted_PAR_tree||Annual intercepted PAR by trees reported by Runyon et al. (1994)|
|PAR_interception_tree||Percentage of IPAR by trees reported by Runyon et al. (1994)||percent|
|intercepted_PAR_total||Total annual intercepted PAR reported by Law and Waring (1994)||MJ/m2/year|
|PAR_interception_tree||Percentage of IPAR by trees reported by Law and Waring (1994)||percent|
|PAR_interception_shrub||Percentage of IPAR by shrubs reported by Law and Waring (1994)|
|PAR_interception_herb||Percentage of IPAR by herb layer reported by Law and Waring (1994)|
|PAR_interception_total||Total percentage of IPAR reported by Law and Waring (1994)|
|tree_biomass_foliage||Foliage (needle) biomass||g/m2|
|tree_biomass_wood||Stem + bark + branch biomass|
|tree_biomass_total||Foliage + wood biomass|
|leaf_litterfall||Leaf litterfall measured at sites 1 and 3 and derived from previously collected data (IBP Forest Science Data Bank) for the other sites|
|foliage_production||New foliage production (fraction of new growth measured in July during maximum canopy development)||g/m2/yr|
|wood_production||Growth in woody biomass of tree stems and branches, including bark (determined from changes in tree diameter estimated from growth-ring measurements)|
|ANPP_tree||Foliage + wood production|
|BNPP||Below-ground production [determined from Raich and Nadelhoffer's (1989) correlation between litterfall and total below-ground carbon allocation]|
|TNPP||Total net primary production (ANPP + BNPP)|
|light-conversion_efficiency_ANPP||Light-conversion efficiency [the ratio of ANPP (in grams per square meter per year) to IPAR (in megajoules)]||g/MJ|
|light-conversion_efficiency_NPP||Light-conversion efficiency [the ratio of NPP (in grams per square meter per year) to IPAR (in megajoules)]|
|light-use_efficiency_ANPP||Light-use efficiency (quantified constraints on above-ground net primary production due to unfavorable temperature, drought, and vapor pressure deficits)|
|light-use_efficiency_NPP||Light-use efficiency (quantified constraints on total net primary production due to unfavorable temperature, drought, and vapor pressure deficits)|
|cover_tree||Percentage cover of dominant tree species||percent|
|cover_shrub||Percentage cover of dominant shrub species|
|cover_herb||Percentage cover of dominant herb species|
|ANPP_tree||Above-ground net primary production of dominant tree species||g/m2/yr|
|ANPP_shrub||Above-ground net primary production of dominant shrub species|
|ANPP_herb||Above-ground net primary production of dominant herb species|
|ANPP_total||Total above-ground net primary production of dominant species|
|total_biomass||Total biomass production of dominant species|
Sample NPP Data Record
|parameter units reference
site_name N/A P & W 1994 Cascade Head Cascade Head Waring's Woods Scio ...
treatment N/A P & W 1994 old-growth N-fixing none control ...
numerical_code N/A P & W 1994 1 1A 2 3 ...
latitude N P & W 1994 45.05 45.05 44.60 44.68 ...
longitude W P & W 1994 -123.96 -123.96 -123.27 -122.61 ...
elevation m R & al. 1994 240 200 170 800 ...
slope percent R & al. 1994 12 0 13 12 ...
aspect degrees R & al. 1994 130 -999.9 160 325 ...
physiographic_province N/A R & al. 1994 western coast range western coast range interior valley lo-elev. west Cascades ...
dominant_species N/A P & W 1994 Tsuga heterophylla Alnus rubra Pseudotsuga menziesii Pseudotsuga menziesii ...
basal_area m2/ha R & al. 1994 98.2 35 51.3 67 ...
stem_density stems/ha (>5cm) R & al. 1994 385 1793 226 870...
cover_tree percent L & W 1994 -999.9 90 90 -999.9 -999.9
cover_shrub percent L & W 1994 -999.9 32.4 91.7 -999.9
cover_herb percent L & W 1994 -999.9 35.2 4.9 -999.9
ANPP_shrub g/m2/yr L & W 1994 -999.9 54 144 -999.9
ANPP_herb g/m2/yr L & W 1994 -999.9 41 6 -999.9
ANPP_total g/m2/yr L & W 1994 -999.9 1265 1310 -999.9
total_biomass g/m2/yr L & W 1994 -999.9 12357 47368 -999.9
The accumulation of biomass, or NPP, is the net gain of carbon by photosynthesis that remains after plant respiration. While there are many fates for this carbon, this data set accounts for above-ground foliage production and woody growth and below-ground production (correlation between litterfall and total below-ground carbon allocation).
OTTER was conducted to develop a strategy to extrapolate point measurements and estimates of ecosystem structure and function across large geographic regions that varied in climate and vegetation. The study was focused on predicting the major fluxes of carbon, nitrogen, and water, and the factors that dynamically regulate them. The OTTER project was conceived to test two major questions: (1) Can a generalized ecosystem simulation model, designed to use mainly parameters available from remote sensing, predict the functioning of forests across an environmentally variable region? and (2) To what extent can the variables required by this model be derived from remotely sensed data? The scientific objectives and scope of the project demanded that a coordinated effort be made to link ground measurements with remote sensing and modeling requirements.
A full spectrum of remote-sensing data and algorithms were evaluated for their satisfaction of parameter requirements of ecosystem models to assess ecosystem structure and function. Ground-based field and laboratory measurements were used to initialize, drive, and validate the predictions of the FOREST-BGC model and of remote-sensing analyses. This OTTER NPP Data Set contains estimates of NPP and associated field measurements from the OTTER transect that were made during the period 1989-1991. Additional OTTER data (including canopy chemistry, meteorology, field sunphotometer, airborne sunphotometer, and timber measurements) can be found at the project web site: http://daac.ornl.gov/OTTER/otter.shtml.
The biomass dynamics data for the OTTER sites are provided for comparison with models and estimation of NPP.
Comparisons of NPP predictions made by the FOREST-BGC model to the measured data resulted in an r2 of 0.82.
Sources of Error
Information not available.
Meteorological stations were installed in secure, open areas < 1 km to a maximum of 15 km from all but the Juniper/Sisters woodland (site 6) at the eastern extent of the transect. The station at Metolius (site 5) served to provide radiation, humidity, and temperature data for site 6, supplemented with precipitation data from a weather station at Redmond, Oregon. Each meteorological station collected air temperature, relative humidity, precipitation, and incident solar radiation (400-1,200 nm) every minute and was programmed to integrate hourly values into an internal data logger.
Intercepted Photosynthetically Active Radiation (IPAR)
IPAR was estimated for trees by Runyon et al. (1994) with a sunflect ceptometer (Decagon Devices, Inc., Pullman, Washington, USA) by measuring the radiance (400-700 nm) transmitted through the tree canopy at each site, and assuming that the remainder was either absorbed or reflected. Measurements at all sites were made on cloudless days during July-August 1991 between 1200 and 1400 local solar time. From 60 to 200 sampling-grid points were required to provide good estimates at each site following procedures described by Pierce and Running (1988).
Law and Waring (1994) measured IPAR for tree, shrub, and herb layers at four forested OTTER sites (and four nearby shrub sites - not reported in this data set). The Cascade Head forested site (OTTER site 1A) consisted of alder (Alnus rubra), a deciduous tree, salmonberry (Rubus spectabilis), an introduced deciduous clonal shrub well established in western Oregon, and swordfem (Polystichum munitum), an evergreen perennial herb. The Corvallis forested site (OTTER Waring's Woods site 2) has Douglas fir (Pseudotsuga menziesii), Himalaya blackberry (Rubus procerus), and swordfem. The OTTER Metolius site (OTTER site 5) was very open and dominated by ponderosa pine (Pinus ponderosa) with 31% cover of the deciduous shrub bitterbrush (Purshia tridentata). The Juniper/Sisters site (OTTER site 6) had a relatively dispersed canopy cover and was dominated by Juniperus occidentalis with the semi-deciduous sagebrush shrub (Artemisia tridentata) and the deciduous green rabbitbrush shrub (Chrysothamnus viscidiflorus). The %IPAR was estimated each layer by measuring incident PAR (wavelength: 400-700 nm) and below-canopy PAR with a sunfleck ceptometer (SF- 80, Decagon Devices, Pullman, Washington, USA). Measurements were made on cloudless days in July 1992, between 1200 and 1400 local solar time. Sampling was conducted on a systematic grid, with 50-200 grid points at a site, depending on homogeneity of canopy cover. The %IPAR was calculated as in Runyon et al. (1994) with the exception that canopy transmittance values were logarithm-transformed in the present study prior to calculation of site median transmittance. This method adjusts for lognormal distribution due to spatial variability of canopies.
Structural data on each stand were collected with techniques modified from those that foresters apply to assess timber volumes (Gholz 1980, 1982). At least 20 circular plots of 50 m2 were established, randomly, in each stand. The diameter at breast height (dbh at 1.37 m) of every tree > 5 cm in diameter was measured in each plot. Total heights and the heights to the base of the live canopy of selected trees spanning the size range (at least 15 per plot) were measured with an Abney level. Trees <5 cm dbh were tallied on a set of 11 smaller (2 x 2 m) subplots. Tree counts and basal area measurements for the plots were used to compute the average number of trees per hectare and to estimate the relative contribution of each tree species to the total basal area. Additional data on tree heights and the length and widths of tree crowns were also measured (Wu and Strahler, 1994). Growth was estimated by measuring ring widths on cores extracted from sampled trees at each site.
Stem, branch, and foliage biomass for individual plants were computed for each species in each plot using the plant measurements and regression equations for species destructively sampled on diverse sites in the Pacific Northwest [Bormann, 1990 (Sitka spruce), Gholz et al., 1979 (all other species)]. The sampling procedures and other documentation are given in Gholz et al. (1979). Above-ground standing woody biomass was estimated by multiplying the measure of average weighted basal area per hectare for each species by the biomass regression equations (Runyon et al., 1994).
To determine foliage biomass, leaf area estimates were converted by measuring specific leaf masses (SLM) on five branches collected from the mid-canopy of trees representing the major species at each site during July 1990 (Runyon et al., 1994). On fresh samples of needles, the projected area was determined with the LI-COR leaf area meter (LAI-3100; LI-COR, Inc., Lincoln, Nebraska, USA), and then dried at 70°C for 24 h and weighed. The average specific leaf area (in square metres per kilogram) of each of the five branches was thus determined, these values were averaged, and the averages were applied to convert LAI estimates obtained with the sunfleet ceptometer to foliar biomass for the tree canopy.
Leaf litterfall was measured only at sites 1 and 3. Previously collected data from the IBP (Forest Science Data Bank) and published information on leaf turnover were used to provide estimates of leaf litterfall at the other sites. Leaf litterfall estimates were derived by assuming that foliage production equals turnover minus 15% mass loss for coniferous species and 20% mass loss for deciduous species.
Leaf Area Index (LAI)
LAI was determined using three different methods (see Runyon et al., 1994 for details):
Net Primary Production (NPP)
NPP estimates included new foliage production and branch, stem, and root growth. Tree mortality would contribute to a reduction in estimates of NPP, but none was noted in 1990. To gauge patterns of foliage biomass production across the transect, the fraction of new growth observed in July during maximum canopy development was measured. In most cases, the same five branches collected for determining specific leaf area were used. The values were pooled for each site, weighted by the LAI of each species, and used to estimate new production from previous calculations of foliar biomass (in grams per square meter per year). A good estimate of new growth was not possible at site 4 (Santiam Pass) because of active defoliation by spruce budworm. Instead, estimates of new foliage production were derived from those published by Gholz for the same site (1982). At site 6 (Juniper), where new foliage was not distinguishable from older foliage in July, data were taken from a separate study to obtain estimates of the new foliage fraction of total leaf biomass Gholz (1980).
Growth in woody biomass of tree stems and branches, including bark, was determined from changes in tree diameter estimated from growth-ring measurements. Increment cores were taken from the first and fifth tree of each species on which diameters were measured to calculate standing biomass. Measurements were made of the current-year's ring width (1990) and of the previous 5 years. No significant difference in annual increment was noted so the average from the previous 5 years served as the basis for computing the annual increment for each site. These values were then applied to the species regression relationships and multiplied by the number of trees per hectare to obtain above-ground woody biomass production (in grams per square meter per year).
Below-ground production was estimated from a correlation between measured annual CO2 efflux from the soil and litterfall derived from a wide range of forests in different climatic zones (Raich and Nadelhoffer, 1989).
These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).
Contact for Data Center Access Information:
Telephone: +1 (865) 241-3952
Gholz, H.L. 1982. Environmental limits on aboveground net primary production, leaf area, and biomass in vegetation zones of the Pacific Northwest. Ecology 63: 469-481.
Olson, R.J., K.R. Johnson, D.L. Zheng, and J.M.O. Scurlock. 2001. Global and Regional Ecosystem Modeling: Databases of Model Drivers and Validation Measurements. ORNL Technical Memorandum TM-2001/196. Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A.
Law, B.E., and R.H. Waring. 1994. Remote sensing of leaf area index and radiation intercepted by understory vegetation. Ecological Applications 4(2): 272-279.
Peterson, D.L., and R.H. Waring. 1994. Overview of the Oregon Transect Ecosystem Research Project. Ecological Applications 4 (2):. 211-225.
Runyon, J., R.H. Waring, S.N. Goward, and J.M. Welles. 1994. Environmental limits on net primary production and light-use efficiency across the Oregon transect. Ecological Applications 4(2): 226-237.
Additional Sources of Information:
Bormann, B.T. 1990. Diameter-based regression models ignore sapwood-related variation in Sitka spruce. Canadian Journal of Forest Research 20: 1098-1104.
Esser, G. 1998. NPP Multi-Biome: Global Osnabruck Data, 1937-1981. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/214
Franklin, J.F., and C.T. Dyrness. 1973. Natural vegetation of Oregon and Washington. General Technical Report PNW 8. Pacific Northwest Forest and Range Experiment Station, Portland, Oregon, USA.
Gholz, H.L. 1980. Structure and productivity of Juniperus occidentalis in Central Oregon. American Midland Naturalist 103: 251-261.
Gholz, H.L. 1982. Environmental Limits on Aboveground Net Primary Production, Leaf Area, and Biomass in Vegetation Zones of the Pacific Northwest. Ecology 63(2): 469-481.
Gholz, H.L., C.C. Grier, A.G. Campbell, and A T. Brown. 1979. Equations and their use for estimating biomass and leaf area of Pacific Northwest plants. Research Paper 41. Oregon State University, Forest Research Laboratory, Corvallis, Oregon, USA.
Marshall, J.D., and R.H. Waring. 1984. Comparison of methods of estimating leaf area index of old growth Douglas fir. Ecology 67: 975-979.
Olson, R.J., J.M.O. Scurlock, S.D. Prince, D.L. Zheng, and K.R. Johnson (eds.). 2012a. NPP Multi-Biome: Global Primary Production Data Initiative Products, R2. Data set. Available on-line [http://daac.ornl.gov] from the Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/617
Olson, R.J., J.M.O. Scurlock, S.D. Prince, D.L. Zheng, and K.R. Johnson (eds.). 2012b. NPP Multi-Biome: NPP and Driver Data for Ecosystem Model-Data Intercomparison, R2. Data set. Available on-line [http://daac.ornl.gov] from the Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/615
Pierce, L.L., and SW. Running. 1988. Rapid estimation of coniferous leaf area index using a portable integrating radiometer. Ecology 69: 1762-1767.
Raich, J.W., and K.J. Nadelhoffer. 1989. Belowground carbon allocation in forest ecosystems: global trends. Ecology 70: 1346-1354.
Waring, R.H. 1980. Site, leaf area, and phytomass production in trees. Pages 125-135 in U. Benecke and M. R. Davis, editors. Mountain Environments and Subalpine Tree Growth. Technical Paper Number 70. New Zealand Forest Service, Wellington, New Zealand.
Waring, R.H., and J.F. Franklin. 1979. Evergreen coniferous forests of the Pacific Northwest. Science 204: 1380- 1386.
Wu, Y., and A.H. Strahler. 1994. Remote estimation of crown size, stand density, and biomass on the Oregon transect. Ecological Applications 4: 299-312.